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PEORIA, Ariz. -- Assistant Chief Greg Dominguez has been a member of the Glendale Police Department for 28 years. But for the first time, he's the subject of an internal investigation, after an alleged off-duty confrontation at a Peoria smoke shop.

These documents show a call to Peoria Police in mid-February. An employee at Spanky's Smoke Shop told officers that a man came into the store and threatened to burn it down because he believed they were selling the synthetic drug spice to his son.

And this wasn't a one time deal, the complaint says the same guy returned and threatened to kill that employee if he did not stop selling to his teen.

A spokesman for Glendale's Fraternal Order of Police confirms that man is Assistant Chief Dominguez. During these confrontations, he says Dominguez wasn't wearing his uniform, and didn't identify himself as an officer.

Staff at Spanky's say in the past his son told them his father was with Glendale Police.

In a statement from the Order, we're told Dominguez was just, "trying to protect a 17-year-old boy from a horrible situation. Dominguez reacted the way any father or mother would react. He put his family first."

As internal investigators continue to look into what happened, Dominguez's focus reportedly now is his family, and keeping up with his police work.

The investigation is not criminal, and only a personnel matter at this time.